Please tell me what this is

[New tank owner]

Hello I was just given a salt water tank and setup over the past 2 weeks this while stuff has formed over one of the live rocks I don’t know if it’s good bad I don’t know much about a salt water tank at all please help me identify this and what should be done about it.

Thank you!

 

[Emberous]

If you are referring to the white blob on your rock, I believe that it is a sponge. They are common hitch hikers and don't require much attention.

 

[JohnVH]

+1